We call the device an electric battery, an accumulator, or simply a battery, which, made up of one or more electrochemical cells, can convert the chemical energy it stores into electricity. Unlike traditional batteries, the chemical reaction that allows them to function is reversible, allowing the battery to be recharged electrically.
Today we have a variety of batteries but there are two major parts that dominate; lithium batteries and lead batteries. What is the correspondence between the two?
Lead vs. lithium batteries
To determine the correspondence between a lithium battery such as a 36v Lithium battery and a lead battery, it is necessary to evaluate a fair number of parameters and analyze the application in detail. There is no universal rule or a predefined number (for example a lithium battery is equivalent to a lead battery with double capacity …!) As much of the variability depends on the power of the application if we talk about starter batteries and energy required if we are talking about traction or deep cycle batteries.
The nominal voltage of the lithium battery and the lead battery must be identical. So if you want to replace a nominal 12V battery, you must choose a nominal 12V LiFEPO4 battery, if you want to replace a nominal 24V battery, you must choose a nominal 24V LiFEPO4 battery and so on.
The nominal capacity of a lithium battery is an unequivocal and unambiguously defined value; this value does not depend on the current with which the battery is discharged. In lead batteries, on the other hand, the capacity decreases exponentially as a function of the intensity of the discharge current.
The battery must always be installed and used in environments whose temperature range is at least equal to that specified in the product specification. The duration of the lithium batteries over time also depends in an important way on the permanence at high temperatures (above 50 ° C), which as is known contribute to speeding up the aging and oxidation process of the electrodes.
The applications
Lithium ion batteries are commonly found in daily electronics, including medical electronics. This battery is the most popular type of rechargeable battery for portable electronic equipment, because it has one of the best energy densities, without memory effects, and experiences slow loss of contents when not in use.
Chemical characteristics, performance, cost, and safety of types of lithium batteries tend to vary. Handheld electronics usually use lithium cobalt oxide-based lithium batteries that have high energy densities, but also have quite well-known safety hazards, especially when damaged. Lithium iron phosphate, lithium manganese oxide, and lithium nickel manganese cobalt oxide have lower energy densities, but live longer and have stronger safety. They are commonly used by electrical equipment, medical equipment, and others.
Lithium Iron Phosphate (LiFePO4) batteries are the safest batteries among Lithium Ion batteries. For example is 36v LiFePO4 battery. And therefore they are the batteries that offer the most possibilities in the field of renewable energy.
This type of lithium battery is utilized in various fields, including cellphone batteries to pacemaker batteries which can last 20 years without stopping. High durability makes this type often used for medical devices with long work duration. Li-Ion batteries have high cycle durability and are also about 30 percent lighter and provide a higher capacity of around 30% when compared to Ni-MH batteries. Self-discharge ratio is around 20 percent per month.
Li-Ion batteries are more environmentally friendly because they do not contain harmful cadmium. Just like a Ni-MH (Nickel-Metal Hydride) battery, even though it does not have the dangerous substance Cadmium, the Li-Ion Battery still contains a few harmful substances that can damage human health and the environment. Therefore, we can recycle (recycle). Don’t throw it anywhere. Dangerous!
Advantages of lithium batteries
3 times more energy density per unit weight than lead-acid
In other words, for the same size, lithium batteries are capable of storing up to 3 times more energy. This is mainly due to the reduced atomic weight of lithium [6.9] versus lead [209]. While a lead-acid battery can store 40 wh / kg, a lithium-ion battery can store up to 120wh / kg. That is why they are suitable when used for medical applications like bone-growth stimulators, glucose monitoring systems, and portable automated external defibrillators.
Higher voltage
Lithium is the most electronegative chemical element there is, offering the highest oxidation capacity. Lithium is 3.16 volts in contrast to 2 volts for lead. Thus, a LiFePO4 battery has a nominal voltage of 12.8 volts after 4-cell series bonding. Or 25.6 volts after joining 8 cells.
Faster loading and unloading
As they have a higher voltage in the cell, they need less current to introduce the same energy. While a lead-acid battery can take between 8 and 12 hours, lithium batteries need a maximum of 4 hours.
No optimal load
Lead-acid batteries do well to be in the upper charging range. With a 20% discharge is when they have the most useful life. Commonly, lithium batteries work better with non-full charges. In fact, it is even preferable not to reach 100% load. They can be discharged almost completely with little damage (as opposed to lead-acid batteries that only withstand discharges of up to 50%).
Longer service life
4000 cycles with 80% depth of discharge. A deep cycle monoblock battery has about 2000 cycles. And a stationary lead-acid battery has 4,000 cycles, albeit at 50% maximum discharge.
Disadvantages
With Lithium-Ion batteries, decentralized energy self-consumption is easier. But…they also have some disadvantages as described below:
Lithium Ion batteries currently present two main problems:
- They are more expensive compared to their lead acid equivalents for the same capacity.
- They are more unstable, and therefore need a cell voltage and temperature controller. That is why lithium Ion batteries need a BMS (Battery Management System) controller.
Beyond their advantages and disadvantages, lithium batteries are the best solution for daily life and also medical needs.
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Interesting related article: “Nobel Prize in Chemistry for work on lithium batteries.”